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2012 BFY Abstract Detail Page
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||W28 - Nanoparticle Scattering of Polarized Light
||This experiment allows students to explore electric dipole radiation in the optical frequency domain. Here, electric dipoles are induced in polystyrene nanospheres suspended in water by the electric field of a linearly polarized HeNe laser beam and the resulting angular distribution of optical radiation in the plane normal to the incident beam is compared to the expected sin2q distribution.
This experiment is highly flexible, with implementations that span a range of simplicity and cost. Details of the construction of the experiment and analysis of the data will be provided. The polarization, particle size and concentration dependence of the angular distribution, and the radial dependence of the irradiance will be discussed. The apparatus will be available for use and typical results will be presented.
For graduate students, the experiment can be extended easily to the study of magnetic dipole (and/or electric quadrupole) radiation by mounting a polarizer in front of the detector. The experiment serves as a handy teaching tool to elucidate the polarization and angular distribution of low order multipole radiation when teaching multipole fields. Many details are contained in Am. J. Phys. [71,1294 (2003)] and Phys. Rev. Lett. [98, 217402 (2007)].
After doing the experiment, students understand how electric dipole radiation explains polarization by reflection (Brewster's angle), polarization by scattering, and the polarization of radiation emitted by circulating charges (as in pulsars).
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Eastern Michigan University